Blood test for pneumonia in children

The need for a blood test for pneumonia in children is determined only by the attending pediatrician. No diagnosis is made on the basis of a single analysis. If pneumonia is confirmed, a second analysis is required later to check the effectiveness of antibiotic therapy. In addition to clinical analysis, if pneumonia is suspected, patients are prescribed biochemistry. It shows metabolic imbalance in the body, the activity of inflammatory processes.

Indications for appointment

Infectious diseases in children are often accompanied by a rise in temperature. If the temperature is high (more than 38.5 ° C) and lasts more than three days, then pediatricians often prescribe a blood test to decide whether antibiotic therapy is appropriate. Laboratory tests are also prescribed in the case of a severe general condition of the child. Thanks to modern technology, it is not necessary to go to the clinic to get tested. It is possible to rent them at home.

Indications for prescribing blood tests:

  • screening / clinical examination;
  • diagnostics of inflammatory diseases;
  • monitoring therapy;
  • differential diagnosis of diseases of the hematopoietic system;
  • in severe forms, the development of septic conditions and complications in the diagnostic protocols, blood biochemistry is mandatory (it makes it possible to assess the work of internal organs and the function of the coagulation system).

Preparation for analysis

The indicators of laboratory tests are influenced by many factors: food / medication intake, diet on the eve of the study, the amount of liquid drunk, physical activity. For a correct assessment of the child’s condition and the correct picture of the disease, it is necessary to follow the recommendations of doctors.

In order for the indicators to reflect the real picture, there are several rules:

  • blood is donated on an empty stomach in the morning from 7-11 o’clock (at least 8 hours after eating, in infants it is allowed to reduce the interval to 2 hours);
  • in infants, the time of blood sampling coincides with the interval between feedings;
  • in 1-2 days, exclude fatty / fried / salty from the menu;
  • the question of taking medications in the morning must be discussed with the attending physician;
  • it is allowed to drink non-carbonated water in small quantities;
  • in 30 minutes give from 50 ml (for children of the first year) to 100-200 ml of water (for older children) for good filling of blood vessels;
  • the main request to mothers is to keep calm, children feel anxiety and fear of the mother;
  • limit emotional / physical stress before the study (at least half an hour);
  • avoid donating blood after other procedures / tests.

Competent preparation is the key to reliable results.

Ways of conducting

As a rule, the material is taken from a finger, in some cases (if biochemistry is necessary), blood is taken from a vein. The injection site is pretreated with antiseptics.

After taking the material, the puncture site on the finger is sealed with a plaster, if taken from a vein, a small bandage is applied for 15 minutes, the arm is bent at the elbow joint.

Decoding the results

The data of the KLA and biochemistry differ depending on the etiology, form and stage of the disease. However, children cannot strictly distinguish between indicators indicating the nature of the pathogen (viruses / bacteria / fungi). Monitoring indicators in complicated forms, in the absence of the effect of antibiotic therapy, allows you to assess the dynamics of inflammation – microbial (resorption, abscess formation) and immunopathological (according to the dynamics of ESR).

What the doctor sees thanks to the blood test:

  1. The number of blood corpuscles.
  2. ESR (according to the old ROE).
  3. Leukoformula.
  4. Hemoglobin level.
  5. Shaped elements: erythrocytes, leukocytes, platelets.

A characteristic marker of any inflammatory reaction, including inflammation of the lungs, is leukocytosis or an increase in the absolute total number of leukocytes. It is these cells that fight infection in the body. It can be from moderate values ​​(10-15 thousand) to significant (up to 40-45 thousand). Severe leukocytosis shows the bacterial nature of the disease. In severe cases, a decrease in the number of leukocytes is possible. Normal leukocyte counts or their decrease (leukopenia) often indicate a viral etiology.

A change in the rest of the elements (platelets / erythrocytes) towards their increase often indicates the severity of the child’s condition, in this case, intravenous rehydration therapy (correction of the water / salt balance) should be carried out immediately. In the recovery period, there is a decrease in red blood cells (anemia), as a general reaction of the body to infection.

Leukocyte formula

An important component of the CBC is the leukocyte formula. It reflects the balance of morphological variants of white cells in percentage.

Types of leukocytes (by morphology / function performed):

  • monocytes;
  • neutrophils (stab / segmented);
  • lymphocytes (T / B);
  • eosinophils;
  • basophilic granulocytes.

The leukogram is read depending on the total number of white cells. In controversial situations, they look at the absolute number of individual types of cells. It depends on the patient’s age. Therefore, pediatricians have special tables. Normally, up to 5 years of age, the values ​​of lymphocytes are much higher than the level of neutrophils. At the age of five, there is a lymphocytic crossover. After this age cutoff, on the contrary, neutrophils predominate.

Bacterial pathogens are characterized by:

  • shift of the formula to the left (stab elements increase and segmented ones decrease) up to young neutrophils and myelocytes;
  • increase / increase in inclusions in the cytoplasm of neutrophils. The more immature neutrophils, the longer the disease will last;
  • if the cause of the disease is viruses – a reverse shift to the right, lymphocytosis.

In severe conditions, eosinopenia and lymphopenia (a decrease in the number of cells) are noted. An increase in the number of these cells is observed before the crisis of the disease and indicates a favorable prognosis.


Reflects the ratio of plasma protein fractions. The increased erythrocyte sedimentation rate (mm / h) is explained by the presence of an inflammatory process in the body and reflects its severity. With this disease, it rises to 30 mm / h. High ESR numbers (up to 70 thousand) are found in inflammation caused by atypical pathogens (legionellosis, mycoplasma pneumonia). In diseases accompanied by polycythemia, these values ​​remain within the normal range, even if the diagnosis of pneumonia is confirmed on X-ray.

A decrease in hemoglobin and erythrocytes is characteristic of destructive forms.

During the period of convalescence, blood counts are restored and gradually return to normal. Leukocytes are the first to return to normal, ESR remains at a high level for another 2-3 weeks. During the normal recovery process, there is a slight increase in the number of eosinophils. If they are reduced / disappeared, there is a high risk of complications.

With inflammation in the lung tissue in the blood test, the main biochemical parameters of the “acute phase” increase: C-reactive protein (CRP), seromucoid, ceruloplasmin, sialic acids, alpha / gamma globulin, LDH (lactate dehydrogenase). Total protein remains normal. If hypoxia (lack of oxygen in the tissues) develops, the gas composition of the blood changes. With atypical pneumonia, the CRP value increases (up to 23%).

When decoding the results of blood tests in a patient with pneumonia, it is taken into account that the transformation of indicators depends on the severity of the disease. The diagnosis of pneumonia is not made by testing the child’s blood. Laboratory diagnostics provides the pediatrician with up to 70% of information that is important for the diagnosis. Only a pediatrician can competently decipher children’s analyzes, taking into account age characteristics.

event_note November 26, 2021

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